Best Metal for CNC Machining: How to Choose

Choosing the right metal is one of the most important decisions for a CNC machined part — it affects strength, weight, corrosion resistance, appearance, machinability, and cost. So what is the best metal for CNC machining? For most parts the answer is aluminum, but the right choice depends on your application. This guide compares the most common CNC metals so you can decide with confidence.

Quick answer

For the majority of parts, aluminum (6061) is the best all-round choice: it's lightweight, corrosion-resistant, affordable, and machines 3–4× faster than steel. Choose a different metal only when your application demands higher strength, better corrosion resistance, conductivity, or a specific look.

CNC metal comparison

Metal	Strength	Weight	Corrosion	Machinability	Relative cost	Best for
Aluminum	Medium	Light	Good	Excellent	$	Most parts, prototypes
Stainless steel	High	Heavy	Excellent	Moderate	$$$	Corrosion, medical, food
Steel (alloy)	High	Heavy	Fair	Good	$$	Strength, wear
Titanium	Very high	Light	Excellent	Difficult	$$$$	Aerospace, implants
Brass	Medium	Heavy	Good	Excellent	$$	Fittings, decorative
Copper	Low	Heavy	Good	Fair (gummy)	$$$	Electrical, thermal

Aluminum — the versatile default

Aluminum CNC machining suits most prototypes and production parts. 6061 is the all-rounder; 7075 adds strength; 5052 adds corrosion resistance. It anodizes well and is the most cost-effective metal to machine.

Stainless steel — corrosion and strength

Choose stainless steel when corrosion resistance, strength, or a hygienic surface matters. 304 is general-purpose; 316/316L is best for marine and medical use. It machines slower than aluminum, so it costs more.

Titanium — strength-to-weight champion

Titanium offers the best strength-to-weight ratio plus biocompatibility, making it ideal for aerospace and medical implants. It's the most expensive and most difficult to machine, so use it only when you truly need it.

Brass and copper — conductivity and easy machining

Brass and copper are the go-to for electrical and thermal applications. Brass (C360) is one of the most machinable metals and looks great; copper has the best conductivity but is harder to machine cleanly.

How to choose the best metal

• Lowest cost / general use: aluminum 6061
• Maximum strength (light): titanium or aluminum 7075
• Corrosion resistance: stainless 316 or titanium
• Electrical/thermal conductivity: copper or brass
• Decorative finish: brass or anodized aluminum
• Tight budget on a complex part: aluminum to cut machine time

Still not sure? Get expert help

Our engineers recommend the most cost-effective material for your part with every quote. Upload your design on our Request a Quote page, or browse all our CNC machining materials and machining services.